Insulation structure



June 16, 1964 Filed June 23, 1958 c. D. DOSKER 3,137,044

INSULATION STRUCTURE 2 Sheets-Sheet l w L W WI INVENTOR. Cornehus D.(Dosker WLMYW ATTorneqs June 16, 1964 c. D. DOSKER INSULATION STRUCTURE2 Sheets-Sheet 2 Filed June 25, 1958 INVEN TOR. Cornehus D.Dosker- BY@MWAWM z wmym Afforneqs United States Patent 3,137,044 INSULATHONSTRUCTURE Cornelius D. Dosker, Louisvilie, Ky,, assignor, by mesneassignments, to Conch'lnternational Methane Limited, Nassau, Bahamas, acorporation of the Bahamas Filed June 23, 1958, Ser. No. 743,539 1Claim. (Cl. .2092) This invention relates to the fabrication of aninsulated space of substantial dimension for receiving tanks of largecapacity housing liquids which need to be maintained at extremely lowtemperature, and it relates more particularly to elements employed incombination with prefabricated panels ofinsulation material to build upan insulation which is continuous in its coverage of a sup portingwalldefining the space, and which, in combination with the insulationpanels, provides a continuous liquid impervious surface to prevent theescape or penetration of liquid in the event such cold liquid comes incontact therewith.

The concepts of this invention will be described with reference tooperation with a liquefied natural gas housed in large volume at orslightly above atmospheric pressure in large tanks of aluminum, alloysof aluminum,

copper, stainless steel, or other austenitic steels or metals capable ofretainingstrength and ductility at the low temperatures of the liquefiednatural gas housed therein. It. will be understood that the sameconcepts can apply regardless of the character of the liquid as long asit is necessary to insulate the space in which the storage tanks arelocated to minimize heat loss into the liquid which otherwise wouldcause excessive vaporization thereof.

Liquefied natural gas is formed mostly of methane which boils at 258 F.at atmospheric pressure. However, liquefied natural gas will usuallyboil at a somewhat higher temperature because of the presence of heavierhydrocarbons, the increase in boiling point depending upon the type andamount of such heavier hydrocarbons, but the boiling point will usuallylie within the range of about 240 F. to 258 F. It is desirable totransport the gas in a liquefied state because the liquid phase occupiesabout ,4 of the volume of the corresponding amount of gas in the gaseousphase thereby to make it practical to transport the gas from a source ofplentiful supply to an area Where a deficiency exists, especially wheresuch areas are separated by a large body of 'water 'to require shiptransportation.

It' will be apparent that, because of the large tempera turedifferential between the liquefied gas and the ambient atmosphere, someheat loss into the liquid will naturally take place, and it is desirableto minimize the heat loss as much as possible to prevent excessive lossof the gas by vaporization or to reduce the cost and size of equipmentfor reliquefaction. Thus, it is essential to insulate the space in whichthe liquid carrying tanksare housed for storage or transportation.

Where the space to be insulated is of substantial dimension, as in thehold of an ocean-going vessel, for transportation of the gas from asource of plentiful supply, Where it is liquefied, to an areawhere adeficiency exists, where the liquid is revaporized, it has beenestablished that the most practical way to insulate the space is toprefabricate panels of substantial dimension of the insulating material,such as panels of 4 x 8' x 1.5, or

t 8' x 8' x 2', and to mount the prefabricated panels on a supportingwall which defines the storage space.

Reference may be made to my co-pending application filed concurrentlyherewith and now abandoned entitled, Insulation Panels for ThermallyInsulating a Storage Space, Serial No. 743,541, filed June 23, 1958, fora description of a panel of the type contemplated for mounting upon thewall and the means for mounting such panels 3,137,044 Patented June 16,1964 thereon. Reference can also be made to my copending application,Serial No. 646,001, filed March 14, 1957, entitled, Heat-Insulated Walland Tank Construction, of which this application is vacontinuation-impart.

Briefly described, such prefabricated insulation panel comprises aninsulation section of substantial thickness sandwiched between inner andouter face plys preferably formed of structurally strong plywood panels.The inner face ply may instead be formed of a metallic sheet or foil, orit may be fabricated to embody a continuous sheet of metal as one of theplys of the plywood panel. The outer face ply is adapted to bestructurally strong for positioning onto the supporting wall, asdescribed in the aforementioned co-pending applications. The insulationsection may be formed of a low density wood, such as balsa wood, quippo,or the like, or of a honeycombed structure formed of paper, veneer orthe like, or of a foamed or molded glass or ceramic which is capable ofstanding up under the extreme temperature conditions existing.

Although the panels may be mounted on the wall so that the edges of oneare in contacting relation with the edges of the adjacent panels toobviate the formation of a space relationship therebetween, it will beapparent that when the cold boiling liquid or other material which needsto be maintained at extremely low temperature is introduced into theinsulated space, as upon filling the tanks, contraction will naturallyoccur in the panels as they are reduced in temperature-the amount ofcontraction being somewhat proportionate to the temperature drop throughthe cross section thereof. Such contraction will naturally cause a spacerelationship to develop between the panels through which heat can flowfrom the ambient atmosphere to the tanks, and through which liquidcoming in contact with the insulation may flow to the supporting wall tocause possible breakdown thereof, or to cause a development of otherextremely dangerous conditions.

Thus, it is an object of this invention to produce and to provide amethod for producing and mounting and maintaining a sealing relationshipbetween the insulation panels mounted upon the supporting wall, whichsealing relationship can be maintained through limitless cycles offilling and emptying of the tanks with the cold boiling liquid.

These and other objects'and advantages of this invention willhereinafter appear, and for purposes of illustration, but not oflimitation, an embodiment of the invention is shown in the accompanyingdrawings in which FIGURE 1 is a vertical view in cross section ofadjacent portions of panels as assembled on a supporting wall;

FIGURE 2 is a sectional view similar to that of FIG- URE 1 illustratingthe preparation of the panels for receiving a sealing membertherebetween;

FIGURE 3 is a perspective view of the wedge insert employed in thepractice of this invention;

FIGURE 4 is a perspective view of a modification of the wedge membershown in FIGURE 3;

FIGURE 5 is a sectional view similar to that of FIG- URES 1 and 2showing the wedge inposition of use between the panels;

FIGURE 6 is a perspective view of an expansion joint employed in thepractice ofthis invention; and

FIGURE 7 is a sectional view similar to that of FIG- URES 1, 2 and 5,showing the expansion joint in the position of use in the assembly. 7

In the drawings illustrating the practice of this invention, the numeral10 represents a supporting Wall which may be the hull of a ship, orinner hull of a double-walled ship defining the hold space, or it may bethe wall of a large housing for a land storage tank or the like. Theprefabricated insulation panels, which are indicated by the numeral 12,are shown as 4' x 8 panels of rectangular shape. Instead, the panels maybe of other interfitting polygonal shape and they may be flat or angled,depending upon the contour of the wall to becovered. The panels are ofsubstantial thickness, usually formed of an outer face 14 and an innerface 16 of plywood, plastic or metal laminate as previously described,with a thick layer 18 of a low density wood or other insulating materialin between. The panels 12 are secured, by the supporting wall in side byside and end to'end relation substantially completely to coverthesurface to insulate the space that is defined thereby. Attachment maybe efiected by bolt and nut means as described in the aforementionedcopending applications.

In effecting a sealing relation between the panels which will permitrelative movement of the panels in a planar direction with the faceresponsive to expansion or contraction, it is desirable to make use of ajoint which is capable of attachment to adjacent surfaces of the paneland which is also capable of movement with the adjacent surfaces underthe cold temperature conditions existing at the inner face withoutbreakdown and without separation. i

For this purpose, use is made of a length 20 of thermal insulatingmaterial or other rather flexible or resilient, heat insulatingmaterial. The length is formed to wedge shape in cross-section with acentral slot 22 cut into the wedge from the outer edge of largerdimension to a distance just short of the apex to subdivide the wedgelengthwise into a pair of laterally spaced legs 24 and 26. This enablesthe leg sections to be flexed in a direction toward and away from eachother while remaining joined in sealing relation at their outer ends.The wedge 20 can be formed of a low density wood, such as balsa wood,quippo, foamed plastics and the like materials, which are capable ofretaining sufficient resiliency and flexibility under the temperatureconditions existing to enable flexure of the sections 24 and 26 withoutcausing separation through the remainder of the wedge. To improve themass integrity of the wedge and its strength and resiliency, it isdesirable to fix a ply of a high strength material to the outer surfaceof the wedge, such, for example, as a wooden veneer 28, as illustratedin FIGURE 3, or preferably a coating 39 of a polyester or the like resinreinforced with one or more plys 32 of glass fibres or other highstrength fibre in fabric form.

After the insulation panels 12 are assembled in the desired relation onthe supporting wall It), the outer edges of the panels are routed out orotherwise formed to provide a groove 34 therebetween which correspondsin cross section with the cross section of the wedge 20 but ispreferably formed to have a width which is slightly less than the normalwidth of the wedge so as to require the wedge to' be rammed into thegroove with sufiicient force to squeeze the wedge and substantiallyclose the slot 22, as indicated in FIGURE of the drawing.

Adhesive 36 is applied to the outer side walls of the wedge 20 with theadhesive preferably limited to the area inwardly of the endof the slot22, or adhesive can be applied to the surface of the panels adapted tobe engaged by the corresponding portions of the side walls of the wedge,or adhesive can be applied to both of the surfaces to bond the lateralsurfaces of the wedge to the adjacent surfaces of the panels whereby oneside of the wedge becomes secured in sealing relation to one of thepanels while the other side of the wedge becomes secured in sealingrelation to the other panel throughout the lengths therebetween. Thus,as one panel contracts in the direction away from the other, therespective sides of the wedge move with the panels resulting in a spreadbetween the sections 24 and 26 about the joining base 38 as the pivot.It is for this reason that it is desirable to bond the side walls of thewedge to the panelsin areas limited to be outwardly from the base of thewedge, otherwise the spreading forces would extend through the entiredepth of the wedge to cause separation therein. The reinforcing andflexibilizing ply 28 or 32 helps greatly in providing flexibility in thesections to enable the legs 24 and 26 to be spread without separation todestroy the sealing connection between the panels.

While the wedge provides a sealing relation between the adjacent panels,the necessity to enable relative movement between the sections24 and 26of the Wedge makes it diflicult to embody a barrier to the penetrationof liquid which might come in contact with the inner surfaces of theinsulation. Thus, another concept of this invention resides in thecombination with the wedge of a vapor and fluid impervious expansionjoint which does not interfere with the operation of the wedge yetprovides a liquid seal between the panels. 7 7

It would not be expected that a material stretchable at ordinarytemperature could be used for this purpose because very few materialswould remain stretchable at the extremely low temperature of about 200F. or less. In accordance with the practice of this invention, thedesirable results are achieved by the use of an elongated strip 40, of afluid impervious sheet of material formed to have a bulbous portion 42extending lengthwise throughout the central portion thereof with flatflaps 44 and 46 extending outwardly fromthe bulbous portion for adistance greater than the space relationship between the panels. Thestrip can be formed of a plastic material which is fluid, andpreferablyalso vapor impervious, and which is capable of standing up under thecold temperatures existing. It can be formed of a Wood, veneer, or ofmetal formed to the desired shape, but it is desirable to mold theexpansion strip of a curable resin ous material, such as a polyesterresin or a polyurethene, or a polyisocyonate resin or the like,reinforced and flexibilized with glass fibres or other high strengthfibres in fabric form.

The expansion strip 49 can be mounted on the panels with the bulbousportion 42 extending inwardly in the direction away from the surface ofthe panels but this might be undesirable because the bulbous portionwould extend into the storage space to be occupied by the tanks. Thus,it is preferred to arrange the strip 4t? in a position of usewith thebulbous portion 42 extending outwardly into an area between theinsulation. For this purpose, a groove 48 is. provided Within the innerface of the wedge 20 dimension to receive the bulbous portion in asubstantially fitting relation therein. In assembly, adhesive 50 isapplied to the outer surfaces of the flaps 44 and 46 inthe areas adaptedto abut against the inner faces of the adjacent panels to efiect asealing relation therebetween. The length of the strip overlying thewedge is kept free of adhesive so that the expansion strip will be freeto move independently of the wedge.

Thus, as the panels contract and increase the space relationtherebetween, the bulbous portion 42 will be shallowed by an amount toprovide the additional width to the strip to enable movement of thebonded sections of the strip with the panels to maintain the fluid tightseal therebetween. At the same time, the sections 24 and 26 of the Wedgewill be able to spread with the panel walls to maintain joindertherebetween. Upon expansion of the panels, the decreased width of theexpansion strip can be compensated by outward flexure of the bulbousportion, while at the same time, the sections 24 and 26 of thke1 wedgecan be flexed in the direction toward each 0t er.

It will be apparent from the foregoing that I have provided a simple andefficient means for maintaining a blocking relation and a fluid-tightsealing relationship between the adjacent prefabricated panels whenmounted in their assembled relationship on a supporting wall. It will beunderstood that various changes may be made with respectto the materialsemployed in the practice of 5 this invention and in the construction andoperation of the elements, without departing from the spirit of theinvention especially as defined in the following claim.

I claim:

Means for maintaining a continuous seal between prefabricated insulationpanels of large dimension mounted in side-by-side relation on asupporting wall and which are subject to substantial reduction intemperature from the temperature of installation to the temperature ofuse with corresponding reduction in dimension due to contraction,comprising a groove in the adjacent outer edges of adjacent panelsdefining a continuous recess therebetween, a spline having across-section corresponding to the cross-section of the recess andfilling the recess formed between the panels, said spline being formedwith a recess in the upper surface thereof and a slot extending from thelower portion of the recess and extending centrally of the spline for adistance short of the bottom of the spline whereby the connectingportion at the bottom of the spline resiliently connects the portions ofthe spline separated by the slot, the side walls of the spline beingbonded to the adjacent walls of the panel in an area corresponding tothe slotted sections, an expansion joint in the form of an elongatestrip of fluid impervious material having a central bulbous portion andbeing dimensioned to have a width bonding the portion overlying thepanels to the underlying surfaces of the panels.

References Cited in the file of this patent UNITED STATES PATENTS1,009,987 Murray Nov. 28, 1911 1,622,311 Fischer Mar. 29, 1927 1,890,954Snyder Dec. 13, 1932 1,965,403 Alvey July 3, 1934 2,073,665 Welch Mar.16, 1937 2,091,061 Waugh Aug. 24, 1937 2,100,238 Burgess Nov. 23, 19372,220,628 Stedman Nov.-5, 1940 2,731,374 De Reus Ian. 17, 1956 2,835,938McElroy May 27, 1958 2,855,636 Donnelly Oct. 14, 1958 2,863,180 BirdwellDec. 9, 1958 2,863,185 Ried Dec. 9, 1958 FOREIGN PATENTS 17,164 GreatBritain Dec. 31, 1914

